Excel Sheet Column Title
Given a positive integer, return its corresponding column title as appear in an Excel sheet.
For example:
1 -> A 2 -> B 3 -> C ... 26 -> Z 27 -> AA 28 -> AB
public String convertToTitle(int n) { if (n <= 0) return ""; String rst = ""; while (n > 0) { int tmp = n % 26; n = n / 26; if (tmp == 0) { rst = "Z" + rst; n -= 1; } else { char cha = (char)(tmp + 'A' - 1); rst = String.valueOf(cha) + rst; } } return rst; }
Excel Sheet Column Number
Given a column title as appear in an Excel sheet, return its corresponding column number.
For example:
A -> 1 B -> 2 C -> 3 ... Z -> 26 AA -> 27 AB -> 28
public int titleToNumber(String s) { if (s == null) throw new NullPointerException("Null String!"); if (s.length() == 0) return 0; int l = s.length(); int sum = 0; for (int i = 0; i < l; i++) { sum += Math.pow(26, l - 1 - i) *(s.charAt(i) - 'A' + 1); } return sum; }
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